An effort exponent arises if additional harvesting requires greater than proportionate additional days at sea, or if there is asymmetry in the cost of harvesting for changes in effort due to the irreversibility of capital investment in vessels. For example, an increase in effort may incur a cost for increases in vessel capacity, as well as direct costs. An equivalent reduction in effort may not save the same vessel capacity cost if the opportunity cost of use of vessels is zero.
From Eq effort as a function of harvest is
arises if additional harvesting requires greater than proportionate 
as 
is